Generator control system



May 14, 1940. l .1. SHAVER 2,200,376

vGENERATOR CONTROL SYSTEM Filed April 2l, 1938 b-w-a 220 [(-60 Jul-znE11-15u51 15g my REG FHEH Immer-111:11

Patented May 14, 1940 PATENT OFFICE GENERATOR CONTROL SYSTEM JohnShaver, Chicago, Ill.,

Switchboard and Sil lll.,

assignor to Kellogg Dllly Company, Chicago, a corporation of IllinoisApplication April 21, 1938, Serial Noi 203,270

4 Claims.

My invention relates to a control circuit for agenerator used forcharging a storage battery. The use of a storage battery, as a source ofpower in telephone exchanges, has become the accepted practice. Thestorage battery is unequalled as a dependable source of power for thisservice ii provision is made for keeping the battery in a properlycharged condition. The floating meth od of charge in which a generatorof suitable capacity is connected in parallel with the battery andoperated continuously, is in general use at the present time.

In telephone exchanges the power load is much heavier during the daythan it is during the night time. If the generator is kept runningcontinuously through the night under practically no load, a glaze tendsto develop on the c'ommutator, and

this glaze may reduce the generator voltage below the proper floatinglimit; therefore, it has been necessary to have an attendant disconnectthe generator from the circuit in the evening and use the storagebattery, alone, as a source of power during the night. The attendantmust then return in the morning to connect the generator into thecircuit to recharge the battery to its former level. In some of thesmaller ex-` changes. the services of an attendant are not alwaysavailable and, therefore, such a system is inconvenient andunnecessarily expensive.

My invention is designed to overcome the necessity of having anvattendant at the station to control the generator. The above difficultyhas been overcome by furnishing a completely automatic circuit in whichthe generator is disconnected from the load during the periods of slightbattery drain and reconnected when the load exceeds a certain point.

A feature of my invention is the provision of means in abattery-charging circuit for automatically connecting and disconnectingthe gen- Y erator into a circuit at certain times.

Another feature of my invention Iis the provision of means in a floatingcharge battery system for disconnecting the generator from the circuitduring periods of low battery drain.

The drawing shows a schematic circuit arrangement of my invention, andthe apparatus disclosed comprises a motor M and a generator G connectedto, land driven by the motorl through shaft S. The coil GO isthe-generator eld coil and rheostat R controls the amount of 'currentgenerated. Anammeter A is connected in a circuit Joining the-negativeside of the storage battery SB to one of the conductors L which lead to(Ci. fil-314) v side. 'I'he flow of current is considered high andprovision is made for including the generator in the supply circuit when8 amperes of current is required to operate the apparatus at the exuchange. Should the battery drain discharge fall below 6 amperes, whichit will do during slack periods, the contact I of the relay BDR willmove to the left with reference to the drawing to cause thedisconnection from the supply circuit of the alternating current. RelayHCR is provided and is maintained energized so long as the proper amountof current is being suppliedby the 220 volt, 60-cycle, three-phasesupply circuit. A high contact relay HCR and a low contact relay LCR areresponsive to the closure oi the high and low contact circuits throughthe armature of the relay BDR. A motor start relay MS is provided andwhen it is energized, due to the closing of the contacts of the highcontact relay HCR, it establishes an actuating circuit for the electricmotor M which operates the generator G to charge the storage battery SiSand supply current to the load. A control relay CR controls theenergization of a battery charging relay BCR, which when energizedconnects the generator output to the storage battery SB.

'I'he operation of my system is as follows: As long as the A. C. supplycircuit is furnishing the proper amount of current the relay ACR will beenergized by current owing from conductor E which leads to the A, C.supply through the winding of the relay ACR and conductor 3 back to thesource of current. Relay ACR is energized by the current owing over thiscircuit and closes 45 its contact 4. If the battery drain is more than apredetermined amount, i. e.. 8 amperes, the contact I of relay BDR willswing to the right to engage contact 5 and close an energizing circuitfor the high contact relay HCR. This relay will 50 be energized bycurrent flowing from the positive side of the storage battery SB throughconductor 0, the winding of the relay HCR, contacts Y5 and I of relayBDR, closed contact 'I' of relay LCR, conductor 8 to the negative sideof storage bat- 55 tery SB. The relay HCR closes its contacts 9, I0, andIl. The closure of contact Il establishes a locking circuit for therelay HCR and removes the relay from the control of the battery drainresponse relay BDR and causes it to remain energized until the batterydrain falls to a predetermined low point. IThe closure of contact 9 ofrelay HCR establishes an energizing circuit for control relay CR whichis operated by current flowing from the positive side of storage batterySB, through conductor 6, closed contact 9' of HCR, conductor i2, closedcontact 4 of relay ACR, conductor i3, the winding of control relay CRand conductor 8 to the negative side of the storage battery SB. Relay CRenergizes and closes its contact i4 to establish an energizing circuitfor the motor start relay MS which relay `will operate by current iowingfrom the positive side of storage battery SB, conductors 6 and l, the

winding of motor start relay MS, normal contact of MS, alternate contactifi of CR, conductor 't to the negative side of storage battery SB. Therelay MS will operate and close its contacts i6, il', and it to connectthe alternating current supply source to the motor M which will beoperated to drive the generator G to generate direct current. The relayMS opens contact I5 and causes the resistance R to be included in aseries circuit with the winding of the relay MS to reduce the amount ofcurrent owing through the winding to prevent its burning out. Theclosing of contact i9 of control relay CR completes a circuit for thebattery charging circuit relay BCR. ".ihis circuit can be traced fromthe winding oi the relay BCR, closed contact i9 of CR, conductor 20,generator output coil GO, conductor 2| to the other side of the windingci relay BCR. The current generated will pass from the output circuitfrom the brushes through the coil of the relay BCR which will notoperate until the voltage output of the generator equals the batteryvoltage". This is to prevent the reversal of current through thegenerator before the generator reaches a speed sufficient to produce therequired voltage output. The battery charging relay BCR will operate andclose its contacts t2 and 23 to connect the generator to the storagebattery terminals and to the battery drain circuit. At this time thegenerator and storage battery are both connected 'to the load andsupplycurrent to operate the apparatus at the telephone exchange.

`When the telephone exchange apparatus draws a load of only 6 amperes,the battery drain response relay EDR will cause the needle i todisengage the contact d and engage the Contact 2t. This will establishan energizing circuit for the low contact relay LCR which circuit may betraced from tine positive side of the storage batd tery SB, conductor G,through the winding of relay LCR, alternate contact iii oi relay HCR,closed contacts 2li and l, normal Contact li ci relay LCR and conductorii to the negative side ci' storage battery SB. The relay LCR will openits contact 'l' to open the locking circuit oi" the high contact relay4HCR which relay will deenergize The operino;`

and restore Si, and Il to normal. of contact ii interrupts theenergizing circuit of the control relay CR which will restore itscontacts ill and i9 to normal. Contact iii interrupts the energizingcircuit of the motor start relay MS which opens its contacts EE, ill andid to disconnect the motor li/.Tl from the source of alternatingcurrent. The motor M being disconnected from its supply circuit willstop'and the generator G will also be stopped. The controlrelay CRrestored contact I9 to 4normal and opened the energizing circuit of thebattery charging relay BCR at 'that time. The relay BCR restoresitsvcon# tacts 22 and 23 to normal and thereby disconnects the; storagebattery SB from the generator supply leads and 2l to prevent thereversal of current through the generator while it is slowing down andcoming to rest.

If at any time the supply of alternating current is interrupted, thesupply relay ACR will be deenergized and open contact 4. I1 the batterydrain is low at this time, it will have no effect on the circuit.However, if the drain is high, the motor start relay will be energized,but the restoration to normal oi the contact 4 of relay ACR Will openthe energizing circuit of the control relay CR which will in turndeenerglze the motor start relay MS and the battery charging relay BCR.i'

Having thus described my invention, what claim is new and desire tosecure by United States Letters Patent is:

l. A generator control system comprising a variable load circuit, astorage battery for the load circuit, a generator having an outputcircuit for charging said battery, a battery drain respense relay havinga Winding connected with the load circuit for actuating said relay inresponse to variations in said load circuit, a contact for said relaymovable in one direction when the drain on the battery'exceeds apredetermined amount and movable in an opposite direction when the drainon the said battery is less than a predetermined amount, a high contactrelay, an energizing circuit for said high contact relay completed whensaid battery drain response relay contact moves in one direction, meansre sponsive to the operation of said high Contact relay for operatingsaid generator, a battery charging relay operable when the output ofsaid generator reaches a predetermined voltage to connect said generatoroutput circuit to said Storage battery, an energizing circuit for thebattery charging relay having circuit closing means therein closed bythe energizing of the high contact relay, c. low contact relay, anenergizing circuit for said low contact relay completed upon themovement of said movable contact in the opposite direction, and meanscontrolled by said low contact relay for stopping said generator.

2. il generator control system comprising a variable load circuit, astorage battery for said load circuit, a generator' having an outputcircuit for charging said battery, a rector tor driving said generator,a battery drain response relay having a winding connected with the loadcirn cuit for act ating said relay in response to variations in saidload. circuit, a Contact tor said n.- lay movable in one direction whenthe drain on the battery exceeds a predetermined amount and movable in asecond direction when the drain on the said battery is less than apredetermined amount, a source of current, a motor start relay havingcontacts for connecting said source oi current to said motor foroperating said motor, a high Contact relay, energizing circuit for saidrelay completed when said battery drain response relay Contact moves inone direction, contacts for said high contact relay for closing anenergizing circuit for said motor start relay whereby said motor isconnected to said source oi current and said generator is operated, abattery charging relayl operable when the output oi' said generatorreaches a predetermined voltage and having contacts for connecting saidgenerator output circuit with said storage battery, an energizingcircuit for the battery charging relay having circuit closing meanstherein closed by the energizing of the high contact relay, a lowcontact relay, an energizing circuit for said low contact relaycompleted when said movable contact of the battery drain response relaymoves in the saici secondi direction, and means controlled by said lowcon tact relay for deenereizing said motor start relay to stop saidmotor and said generator.

3. A generator controi system comprising a variable load circuit, astorage battery connectent across the load circuit, a generator havingan output circuit for charging said battery, a motor for driving saidgenerator, a drain response re lay having a winding connected in serieswith the load circuit for actuation in response to t-'ariam tions insaid load circuit, a contact for said reiay movable in one directionwhen the drain ci tiie load circuit exceeds a pre errnined ernennt andmovable in the other direc on when tiie ci loaci circuit is less ti'iana precie eil amount, a source ci current, a motor stair, having contactsici' connecting said source o cuirrent with said motor for operatingsaid rnotor, a battery charging relay operable when tiie output oi saidgenerator reaches a predetermined voitace and having contacts i'orconnecting said eenu erator cutout circuit with said storage battery, acontrol relay having contacts for closing euer giaing circuits tor tinemotor start reiay and ior the battery charging relay, a high contactrelay having an enereficine circuit which is completed when the drainresponse relay contact moves in one direction, contacts actuated bysaicl Inicio contact relay for closing an energiznng circuit for saidcontrol relay ior thereby closing energizing circuits for said inotcrstart relay and saioi tery charging relay, a low contact relay, an eneroelaine circuit tor salici low contact relay concE piloted when titemovable contact ci the drain ce sponse relay moves in the otherdirection, and means controlled by saidl low contact relay fordeenergizing said motor start relay to stop said 'motor and saidgenerator.

' ing connected with the load circuit for actuation in response tovariations in said load circuit, a contact for said relay movable in onedirection when the drain oi the loaol circuit exceeds apredeterniinediainount and movable in the other direction when tiledrain ci the load circuit is less than a predetermined amount, source cicurineat" lor connecting said source' oi current with sa' motor ioroperating saisi inotor, a battery charging relay operabie when out cisaisi gener. tor reacties e. volt age hay f en energiainfj: circuit enticon tacts ier collincting sain? generator output cir1 cuit with storagebattery, a control. reiey for closing tifie energizing circuit ici* onecattery charging relay and ici' controlling said conncct-n ing means, anigh contact relay an euere sizing circuit which. is completed when thedrain response relay contact moves in one direction, contacts actuatedby said high contact relay for closing an energizing circuit for saidcontrol re lay for thereby closing the energizing circuit for saidbattery charging relay and for starting the motor, a low contact relay,an enel-elaine circuit ior said low contact relay completed when themovable contact of the drain response relay moves in the otherdirection, and means controileii by said low contact relay for actuatingsaid connection means to stop said motor and said generator.

JOHN SHA

